Music boxes with piezoelectric pickups



Aug. 11, 19-70 JuNz'ou ISHIKAWA T 3,524,007

I MUSIC BOXES WITH PIEZOELECTRIC PICKUPS Filed Feb. 23 1968 2 Sheets-Sheet 1 JUA/Z ou A WA ////\05/// Km: GflWA INVENTOR.

Aug. 11,1970 JUNZQU s -n w .ETAL 3,524,007

MUSIC BOXES WITH PIEZOELECTRIC PICKUPS Filed Feb. 23, 1968 2 Sheets-Sheet I SPEAKER 1O AUDIO AMPLIFIER POWER SOURCE Julvzou /'5#/KA WA ///R05/// K/TA/IWA INVEN TOR.

United States Patent US. Cl. 841.14 7 Claims ABSTRACT OF THE DISCLOSURE A music box for generating at least one melody in playing a comblike vibrator by a rotating tune drum, where a plate of piezoelectric transducer is adhered on the surface of the base of the comblike vibrator, and an electric signal of the melody is derived from the plate of piezoelectric transducer to generate acoustically the melody. In a modification a push button switch and cam-contact arrangement provides for a limited rotation of the tune drum. In a second modification a pair of music boxes with different melodies may be operated by a push button switch at two locations such as a front door and a back door.

This invention relates to a music box and more particularly to an electronic music box for generating at least onemelody in playing tune drum.

There have been heretofore proposed electronic music boxes of the type which provides, with a comblike vibrator having a plurality of vibratory teeth of different length, a tune drum rotatable on the axis thereof and having a plurality of small projections on the cylindrical surface thereof to play the vibratory teeth in accordance with a desired melody, and a transducer for detecting an electric signal of the melody from the vibration of the vibratory teeth to generate acoustically the melody. In the conventional electronic music box, however, a magneto-electric transducer such as magneto-electric pick-up device, is employed as the transducer. Accordingly, while the conventional music box cannot have so good detection characteristic of melody and has a relatively high price, it has a considerably complicated construction and a large size.

An object of this invention is to provide a music box capable of eliminating the above mentioned defects of the conventional ones and having a simple construction and a good detection characteristic of at least one desired melody.

In accordance with the feature of this invention, the music box of this invention is provided with a plate of piezoelectric transducer adhered to the surface of the base of a comblike vibrator played by a rotating tune drum so as to detect an audio signal of a melody from the comblike vibrator.

The principle of this invention will be better understood from the following more detailed discussion in conjunction with the accompanying drawings, in which the same or equivalent parts are resignated by the same reference numerals, characters, and symbols, and in which:

FIG. 1 is a diagrammatic view for illustrating an embodiment of this invention;

FIG. 2 is a diagrammatic side view for illustrating a characteristic part of this invention;

FIG. 3 is a diagrammatic plan view for illustrating another embodiment of the invention; and

FIG. 4 is a block diagram for illustrating another embodiment of this invention.

The construction of the music box according to this invention will first be described with reference to FIGS. 1 and 2. The music box of this invention comprises a driving motor 1, source terminal means 2, a switch 3, a comblike vibrator 4, a tune drum 5, coupling means 6, a plate 7 of piezoelectric transducer, audio terminal means 8, an amplifier 9 and a speaker 10. The switch 3 is arranged between the driving motor 1 and the source terminal means 2, so that the driving motor 1 is energized by the electric AC. or DC. power supplied from the source terminal means when the switch 3 is established to its ON-state. The comblike vibrator 4 has a plurality of vibratory teeth 12 of different length as shown in FIG. l. The tune drum 5 is rotatable on its axis 13 and has a plurality of small projections 11 on its cylindrical surface 15 to play the vibratory teeth 12 of the comblike vibrator 4 in accordance with the predetermined melody. The coupling means 6 comprises a flexible coupling by way of example and is employed for transferring the rotation of the shaft 14 of the motor 1 to the axis (shaft) 13 of the tune drum 5 so as to rotate the tune drum 5 at a constant rotation speed by use of the rotation of the driving motor 1. The plate 7 of the piezoelectric transducer is adhered on the surface of the base 16 of the comblike vibrator 4. The audio terminal means 8 is prepared on one surface of the plate 7 and at a point electrically connected to the other surface of the plate 7 so as to derive an audio signal from the plate 7 of the piezoelectric transducer. The amplifier 9 amplifies the audio signal. The speaker 10 is connected to the output of the amplifier 9 and generates acoustically the melody.

As mentioned above, the plate 7 of piezoelectric transducer is adhered on the surface of the base 16 of the comblike vibrator 4 in consideration of following inventive idea of this invention:

(1) While the base 16 is fixed on a frame (not shown), the base 16 of the comblike vibrator 4 is vibrated by the vibration of the vibratory teeth 12 in accordance with the played melody.

(2) Because of the above-mentioned phenomenon, the melody may be detected as an electric signal from the base 16 of the comblike vibrator 4 by means of the plate 7 of the piezoelectric transducer.

The above-mentioned music box of this invention operates as follows. At first, the switch 3 is switched to its ON-state, and the tune drum 5 is therefore rotated at a constant rotation speed along an arrow A, as shown in FIG. 2. Accordingly, the projections 11 on the surface 15 of the tune drum 5 play and vibrate the vibratory teeth 12 of the comblike vibrator 4 in accordance with the melody. The vibration of the vibratory teeth 12 is transferred to the base 16 of the comblike vibrator 4 and detected piezoelectrically by the plate 7 according to the above-mentioned principle. Therefore, the audio signal of the terminal means 8 is an electric signal corresponding with high fidelity, to the melody and converted to an acoustic signal corresponding to the melody by use of the amplifier 9 and the speaker 10. An ear-phone may be employed in the place of the speaker 10. If necessary, the output of the amplifier 9 may be connected to a transmission medium to transmit the audio signal for the melody at a distant place.

As the plate 7 of the piezoelectric transducer, a transducer utilizing piezoelectric transverse effect or piezoelectric longitudinal effect may be employed. Examples of the material of the plate 7 are Rochelle salt, ADP, KDP, LH (i.e., LiSO -H O), porcelain of BaTiO porcelain of Pb(Z -Ti) O porcelain of niobate, EDT (i.e.;

C4H6O6 2 s z) DKT (i.e.; K C O /2H O) and rock crystal etc. The size of the plate 7 is for example 3 millimeters in length, 3

millimeters in width and 0.5 millimeter in thickness to obtain a sufiicient output voltage from the audio output terminal. Accordingly, the transducer of the music box of this invention can be formed into a much smaller size than the conventional one. If the plate 7 uses the piezoelectric transverse effect, the audio terminals 8 are prepared at two longitudinal ends of the plate.

FIG. 3 shows another embodiment of this invention, in which the coupling means 6 comprises a worm gear 17 connected to the shaft 14 of the motor 1, a small worm wheel 18, a gear 19 connected to the worm wheel 18, coupling gears 20 and 21 and a driving gear 22. By means of these coupling gears, the tune drum is driven. In this embodiment, a cam 16 is fixed to the shaft 13 to switch contacts 3a and 3b which are respectively connected to two pairs of terminals (t and t and (t and t Terminals t and f are employed as the power source terminal means 2. The terminals t and 1 are connected to the switch 3, such as push button switch, and the terminals 1 and L; are employed to switch the electric power to be supplied to the amplifier 9. Terminals t and t are connected to the input of the amplifier 9. Accordingly, if the switch 3 is switched to its ON-state, the tune drum 5 is driven through the gears 17, 18, 19, 20, 21 and 22. In this case, if the cam 16 is so designed that the contacts 3a and 3b assume the ON-state at a period only during a predetermined rotation angle of the tune drum (egg 1: or 21r radians) when the rotation of the tune drum 5 starts by switching the switch 3, the tune drum 5 can be rotated by the predetermined angle for each switch operation of the switch 3.

FIG. 4 is another embodiment of this invention, in which two boxes (BOX-I and BOX-II) each providing with such means as described with reference to FIG. 3 are employed. A power source 2a is employed for rectifying an A.C. power supplied from the power source terminal means 2. As understood from the description as to FIG. 3, BOX-I or BOX-II generates the audio signal so as to apply the amplifier 9 by switching either of the switches 3. Since this embodiment provides different melodies, this embodiment is suitable to a sign-phone controllable from two places, such as a front door and a back door of a personal house.

Since the detection means of the music box of this invention has a very small size and can be easily arranged without difiicult adjustment works, the music box of this invention can be easily fabricated into a compact size with a low price. Therefore, the music box of this invention has wide applicable fields.

While we have described particular embodiments of our invention, it will of course be understood that we do not wish our invention to be limited thereto, since many modifications and changes may be made and we, therefore, contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim is:

1. A music box for generating at least one melody, comprising a driving motor, power source terminal means for supplying electric power to the motor, a switch arranged between the source terminal means and the driving motor to switch the electric power, a comblike vibrator having a plurality of vibratory teeth of different length, a tune drum rotatable on the axis thereof and having a plurality of small projections on the cylindrical surface thereof to play the vibratory teeth of the comblike vibrator in accordance with the melody, coupling means for rotating the tune drum at a constant rotation speed by use of the rotation of the driving motor, a plate of piezoelectric transducer adhered on the surface of the base of the comblike vibrator, audio terminal means for deriving an audio signal from the plate of piezoelectric transducer, an amplifier for amplifying the audio signal, and an electro-acoustic transducer connected to the output of the amplifier.

2. A music box according to claim 1, in which the piezoelectric transducer generates the audio signal by piezoelectric transverse effect.

3. A music box according to claim 1, in which the piezoelectric transducer generates the audio signal by piezoelectric longitudinal effect.

4. A music box according to claim 3, in which the piezoelectric transducer comprises a plate of piezoelectric porcelain plate.

5. A music box according to claim 1, in which the switch comprises a push-button switch and a cam switch connected in parallel to each other, the cam switch assuming the ON-state at a period only during a predetermined rotation angle of the tune drum when the rotation of the tune drum starts by switching the button switch.

6. A music box according to claim 5, in which the cam switch provides with another contact to switch the power source of the amplifier during the predetermined rotation angle only.

7. A music box according to claim 1, in which the music box further comprises a second driving motor, a second switch arranged between the source terminal means and the second driving motor, a second comblike vibrator having a plurality of vibratory teeth of different length, a second tune drum rotatable on the axis thereof and having a plurality of small projections on the cylindrical surface thereof to play the vibratory teeth of the comblike vibrator in accordance with another melody different from the said melody, second coupling means for rotating the tune drum at a constant rotation speed by use of the rotation of the second driving motor, a second plateof piezoelectric transducer adhered on the surface of the base of the second comblike vibrator, second audio terminal means for deriving an audio signal from the second plate of piezoelectric transducer to apply the signal to the amplifier.

References Cited UNITED STATES PATENTS 7 2,018,924 10/1935 Ranger 841.14 X 2,309,703 2/1943 Lovell et al. 84-1.14 X 3,229,021 1/ 1966 Baschet 841.14 3,429,977 2/ 1969 Ying-Tsai 84-1.14

WARREN E. RAY, Primary Examiner 

